The Flying Saucer Shape is a special case of the Two Space Notchers (c) James Davies, moreover Two Space Notchers Not Fully Connected. The term Flying Saucer I made up myself and I'm not convinced it will make history. I just needed a pagename a bit catchier than Two Space Notcher With Both Weak Points Occupied. --DieterVerhofstadt.
See Kanazawa Problem 23 for a interesting problem involving the Flying Saucer Shape.
What matters is that the black group is blocked at the second line ( stones), and that its weak spots are occupied (
stones). What does not matter is whether the circled liberties are occupied or not.
Let's see some attempts by Black to live. For a general treatment, see Two Space Notchers Not Fully Connected.
White cuts at the other side than the one Black protects, then gives atari. She finishes off with , keeping Black at one eye. The position is symmetric, so if
at 3 then
at 5.
Black ends up with a 3 point big eye with already at the vital point.
After , Black has a shape similar to six on the second row. He's dead.
gives major resistance, but after
, she can almost fill Black's eye space with three stones any time.
This reverts to attempt 3.